Nibe Fighter 360p ashp costing me loads to run

John_Pierpoint

It takes a great act of faith on the part of a tenant to watch the meter whizzing round (or the little red light flashing for each watt) in the hope that the "pump" bit of the heater will cut in and start providing heat comparable to that provided by a modern gas boiler.
Everything they have ever learned, since their dad accused then of leaving the light on overnight, goes against taking the chance that keeping the house continually hot is cheaper than letting it cool down overnight and when away working during the day time.
I would expect the landlord to put his money where his mouth is and pick a model tenant to demonstrate for a month at the landlord's expense in say December. The incentive could be that if the tenant could out-perform a similar neighbour on say modern night storage radiators - then they would get free electricity for the rest of the winter.
It is time for these landlords to put up or shut up.

lovesfarmbpha

oh we did better than that ...we offered that if they installed a gas boiler and annual house bills were higher than half that of the ones found with the exhaust air heat pump then we would pay for the boiler and install costs but if we managed to have bills less than half using gas then they would have to leave the gas boiler in place and pay the difference we had paid over the years...they declined our offer

lovesfarmbpha

albyota wrote: »

Hi, I think you will find that the 'Boiler Interlock' referred to by MCS 3005 v3, is where a Bivalent system exists, i.e a Heat pump that provides the heating and hot water requirements for the dwelling most of the year.... and down to say minus 5 degrees, then a backup Gas / Oil / LPG boiler takes over at lower temps, the 'interlock' being the controls 'Frost stat / Relay, which automatically switch off the heat pump and fire up the boiler, so that they cannot be run together.

your Nibe exhaust air heat pump is the only source, therefore, no requirement for an interlock.

AL

Its found in the domestic heating and hotwater guidance 2008. Section * (heat pumps) states that if the heatpump alone cannot heat the water to above 60C then yo must use a back up power (in this case immersion element at 6kw)
The NIBE 360 & 200 only heat the water to max 56C using heat pump power.
Due to this you default to using grid power which thus defaults to section 4 (electrical heat and hotwater) which state you require a boiler interlock...
The Domestic heating guidance is aligned to building regs.
if the heat pump alone took the water to above 60C then yes an interlock would not be required... unfortunately it does not take the water to 60C alone.

lovesfarmbpha

grahamc2003 wrote: »

I think there's a couple of misconceptions in these two paragraphs. (I went through a similar exercisea few months agfo, I think on this thread, and convinced myself that the theory it works under is sound - afterall, these things work in other countries).

Yes - as a first cut approximation, 7 degrees of the heating comes from (most of) the electricity consumed (by the compression of the working fluid), but no, that doesn't mean the other 14 degrees comes 'from the outside air'. The other 14 degrees comes from the exhaust air, which is at 21C in your example. So in theory, all the heat pump has to do is lower the exhaust air from 21C to 7C - and that's very easy to do, considering Ecodans cool the outside air from -5C to probably -40C (imo) in order to extract the 8kW they supply. In fact, you've stumbled across the great advantage of exhaust air heatpumps (in theory!) - that is the avoidance under normal circumstances of icing, which is the real pain in the neck for non-exhaust type air pump.

Another way of looking at the theory of these exhaust heat pumps is that, at steady state (i.e. once the temperature has reached the required temp), all the heatpump does is supply say 2kW to replace the house heat loss, and 'lend' and then recover about 6kW to the air as it (quickly!) passes through the house. In theory. A couple of points arise from that - firstly I expect it will be very painful (in terms of high electricity use) initially getting the house up to the steady state temperature, when the exhaust temp is low (perhaps there are icing issues). Perhaps the 8kW heating elements are used at this time (for a few hours!) to try to quickly get to the steady state temp and into the (theoretically) efficient operating regime. Another point is that it's implicit in the theory that air entering and exiting the house is under very strict control, and not entering or leaving by gaps/flooboards/windows/letter boxes and any other leaks.

For the benefit of the public just to confirm the incoming air on these units is not preheated and is just that incoming outside air so your dragging in lets say 7C outside air directly into the building at 110 M3 per hour ...your air in your home is 21C because you have heated it to that via radiators ...your sucking up the 21C air and using it to lets say double its power using circa 850watts of grid power to run the boiler. So what you actually doing is heating the outside air that enters your home by removing the hot air..you dont need to be a thermodynamics expert to see a problem.
So lets apply that to lets say a gas run house ...thats the same as me saying "hey john open the front and back door because we need some fresh air and just turn up the boiler to compensate" yes I can hear your response.
Not only that once the system has finally done its thing it continues to throw the hot air out with no other use than to ventilate the home.
The boiler intelrock issue occurs in heating mode...if your home hits its required temp the circulation pump does not stop as it does with every other boiler in the world ,,,oh no,,,it carries on running (only at 100watts so 2.4Kwhs for the day ) but this also draws the hotwater temp down within the system so it then has to boost the tank heat more often than a boiler with an interlock...

jasonoldy69

Has the Facebook page gone?

grahamc2003

lovesfarmbpha wrote: »

For the benefit of the public just to confirm the incoming air on these units is not preheated and is just that incoming outside air so your dragging in lets say 7C outside air directly into the building at 110 M3 per hour ...your air in your home is 21C because you have heated it to that via radiators ...your sucking up the 21C air and using it to lets say double its power using circa 850watts of grid power to run the boiler. So what you actually doing is heating the outside air that enters your home by removing the hot air..you dont need to be a thermodynamics expert to see a problem.
So lets apply that to lets say a gas run house ...thats the same as me saying "hey john open the front and back door because we need some fresh air and just turn up the boiler to compensate" yes I can hear your response.
Not only that once the system has finally done its thing it continues to throw the hot air out with no other use than to ventilate the home.
The boiler intelrock issue occurs in heating mode...if your home hits its required temp the circulation pump does not stop as it does with every other boiler in the world ,,,oh no,,,it carries on running (only at 100watts so 2.4Kwhs for the day ) but this also draws the hotwater temp down within the system so it then has to boost the tank heat more often than a boiler with an interlock...

Hi - I notice in this response was the quote of my previous post, but I'm having difficulty seeing which points of mine you are replying to, and also I can't really work out whether you are agreeing with me or disagreeing. Maybe I'm simply not reading it correctly. I'm interested in your reply to my thoughts (whether you agree or disagree with them), so (if you can be bothered), could you take one point or sentence at a time and give your thoughts on those specific points?

One point I can reply to is this

<i>Not only that once the system has finally done its thing it continues to throw the hot air out with no other use than to ventilate the home. </i>

which is a critical issue. The hot air isn't simply thrown out in these exhaust heat pumps - the warm exhaust air is used as the heat source for the whole system (in steady state) and has (some of) its heat removed before finally being exhausted out the house (as I think you implied earlier in your post, which is why I find the quote a bit puzzling)

jasonoldy69

http://youtu.be/7bhRlFEiU9g

Watch as it's blowing away warm air...

londonsouth

NIBE 205 F does not blow the outside air in. There are two openings in the walls that simply let the air in. The cover on it is 5 cm away from the edge of the pipe that is open and connect the outside world with the living room. It just blows. Unbearable. I have put the sliding cover to help a little bit but not to entirely block it. At the end had to sellotape a plastic sheet over it as it does not help much. I have just bought a Black and Decker Thermal Leak Detector. The temperature of the cover is still 6C lower that the room and the wind still blows around the edges. The result is obvious. Loss of heat

Question:

I feel I will never get any warmth until I completely close these. What would be the negative effect of me entirely blocking these openings if any?

grahamc2003

jasonoldy69 wrote: »

http://youtu.be/7bhRlFEiU9g

Watch as it's blowing away warm air...

Would be interesting to get Nibe's view on any possible explanation under any circumstances for that set of temperatures! Obviously, if that is typical, then there's something drastically wrong (maybe the installers got their heat exchangers mixed up, and cool the incoming air and heat the exiting air! ... that's a joke btw (i hope!).

Even that throws up an issue - how come the room temp is below the exhaust air temperature?

At least the room temperature is warm enough - was it warm enough during the winter? (The impression I got from users on this thread is that they cost a bomb to run while at the same time not warming any rooms).

jasonoldy69

grahamc2003 wrote: »

Would be interesting to get Nibe's view on any possible explanation under any circumstances for that set of temperatures! Obviously, if that is typical, then there's something drastically wrong (maybe the installers got their heat exchangers mixed up, and cool the incoming air and heat the exiting air! ... that's a joke btw (i hope!).

Even that throws up an issue - how come the room temp is below the exhaust air temperature?

At least the room temperature is warm enough - was it warm enough during the winter? (The impression I got from users on this thread is that they cost a bomb to run while at the same time not warming any rooms).

The boiler has been tested and re-setup, only a few days ago as well. With no faults found.

Winter was unbearable. The rooms never reached 19C, the showers lasted 10mins even with the hw boost. We closed a few rooms so theres less to heat. We closed the vents on some days to stop the draft (And, yes, we know we're not supposed to). But funilly enough, it got warmer closing them.

We used the hw boost for about an hour a day, didn't want to touch the winter mode. I didn't want to try the winter mode, because I don't have disposable cash.

If you think about it, if you heat the house with the immersion in the winter, the boiler is still throwing it all outside...